(physics) A minor stable isotope of titanium, ⁴⁹₂₂Ti, having twenty-two protons and twenty-seven neutrons; it amounts to about 5% of the element in nature

A class of two-handed double-trapeze dinghy (from its maximum length of 16 feet, approx. 4900 millimetres). / (historical) A miner or other person who took part in the California gold rush of 1849.

plural of 49er